Past lexical decision studies investigating,o the number of meanings (NOM) effect have produced mixed results. A second variable, the relatedness among a word's meanings, has not been widely studied. In Experiment 1, Relatedness (High or Low), NOM (Many or Few), and nonword condition (legal nonwords or psuedohomorphones) were manipulated in lexical decision. No significant effects of NOM or Relatedness were observed in the legal nonword condition. However, in the pseudohomophone condition, Relatedness and NOM both produced significant main effects, and an interaction. Words with few, unrelated meanings produced the slowest response times (RTs); all other words produced statistically equivalent RTs. Results of the pseudohomophone condition of Experiment 1 were replicated in Experiment 2, except the main effect of NOM was not significant. The overall unreliability of NOM effects in these (and previous) experiments lead us to question the contribution of NOM to the observed interaction NOM metrics are often confounded with relatedness; words with many meanings tend to have highly related meanings. The results show that relatedness among meanings can influence lexical decision performance; the challenge is now to explore alternative measures, other than simple enumeration. (C) 1997 Academic Press.
